Door knob



FIG. 1 is a perspective view of a door knob showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof; and,

FIG. 4 is a top view thereof, the bottom view, the right side view andthe left side view being mirror images.

The broken line structure is included for the purposes of illustratingenvironmental structure and forms no part of the claimed design.

The ornamental design for a door knob, as shown and described.